1. Field of the Invention
The present invention relates to valve assemblies for selectably determining fluid flow through one of two tubes used, e.g., in a steam iron. More particularly, the present invention relates to improvements in a pinch valve assembly wherein the tubes are isolated from frictional wear from sliding members.
2. Description of the Prior Art
In the art of pinch valves of the kind operable to selectably effect fluid flow through one of two flexible tubes, it is customary to employ a two-way tube clamping device that selectably engages the tubes to shut off fluid flow through one tube while permitting fluid flow through the other tube. This kind of valve is particularly suited for use in conjunction with controlling the flow of water through a steam iron wherein water is contained in a reservoir. Water is pumped from a reservoir towards the valve through a pair of tubes and thereafter allowed to flow from the valve towards a spray nozzle exit or a steam release base plate depending on the tube blocking condition of the valve.
Heretofore, valves operable for pinchably closing a flexible section of tubing in the valve have encountered significant problems in terms of providing a tube clamping device that reliably operates over extended periods of time, i.e., for the life of the appliance containing the valve. In this regard, it is highly desirable to provide a tube clamping device in the valve that continually operates in a manner whereby frictional wear of the tubes is avoided in the presence of repeated tube opening and closing operations. Another major concern in providing a lasting valve is that they continually operate to completely close the pinched tube to block fluid flow, and thus avoid maintenance to correct fluid leakage therethrough. For example, U.S. Pat. No. 3,635,251 entitled "Valve", granted on Jan. 18, 1972 to Stanley L. Gaines, discloses a bistable acting valve having a spring member operable to flex between two positions for selectably closing one of two flexible tubes. One distinct problem presented by this kind of valve arrangement resides in its use of a pretensioned spring to collapse the tubes. Over a period of time, the pretensioning forces of the spring will increasingly lessen towards becoming incapable of completely collapsing the tube. Through Gaines suggests in his patent that the spring tensioning forces are adjustable, by moving the spring anchor position, such an adjustment is difficult and sensitive to make requiring the service of one skilled in the art.
Regarding frictional wear of the flexible tubes caused by a sliding action delivered from the clamping member onto the tubes in repeatedly opening and closing the tubes, if remained unchecked, sliding frictional wear will result in the tube wall being worn thin or even ruptured requiring difficult and costly tube replacement. Two examples of valves wherein the flexible tube(s) are exposed to frictional sliding engagement with clamping members are U.S. Pat. Nos. 3,411,534 entitled "Four-Way Valve", granted Nov. 19, 1968 to Frank L. Rose, and 4,177,969 entitled "Flow Control Device", granted Dec. 11, 1979 to Paul Sieber-Muller.